The American Civil War began on April 12, 1861, when Confederate forces attacked Fort Sumter in South Carolina, following decades of tension over states' rights and slavery. The Union was determined to maintain the integrity of the United States, while the Confederate states sought to preserve their way of life, including the institution of slavery. The Battle of Fort Sumter marked the start of four bloody years of fighting that resulted in the emancipation of enslaved people and the preservation of the United States as a single nation.